Make the SQLite3 driver more generic

The changes in this commit should make it more practical to:

- Allow the driver to decide for itself whether to try creating a PDO object if its own requirements are not met
- Have any driver use a generic schema update procedure
- Use the same constructor for native and PDO SQLite

lib/Database.php

@@ -27,7 +27,7 @@ class Database {
 
     public function __construct($initialize = true) {
         $driver = Arsse::$conf->dbDriver;
-        $this->db = new $driver();
+        $this->db = $driver::create();
         $ver = $this->db->schemaVersion();
         if ($initialize && $ver < self::SCHEMA_VERSION) {
             $this->db->schemaUpdate(self::SCHEMA_VERSION);

lib/Db/AbstractDriver.php

@@ -6,15 +6,13 @@
 declare(strict_types=1);
 namespace JKingWeb\Arsse\Db;
 
+use JKingWeb\Arsse\Arsse;
+
 abstract class AbstractDriver implements Driver {
     protected $locked = false;
     protected $transDepth = 0;
     protected $transStatus = [];
 
-    abstract public function prepareArray(string $query, array $paramTypes): Statement;
-    abstract protected function lock(): bool;
-    abstract protected function unlock(bool $rollback = false) : bool;
-
     /** @codeCoverageIgnore */
     public function schemaVersion(): int {
         // FIXME: generic schemaVersion() will need to be covered for database engines other than SQLite
@@ -25,6 +23,52 @@ abstract class AbstractDriver implements Driver {
         }
     }
 
+    public function schemaUpdate(int $to, string $basePath = null): bool {
+        $ver = $this->schemaVersion();
+        if (!Arsse::$conf->dbAutoUpdate) {
+            throw new Exception("updateManual", ['version' => $ver, 'driver_name' => $this->driverName()]);
+        } elseif ($ver >= $to) {
+            throw new Exception("updateTooNew", ['difference' => ($ver - $to), 'current' => $ver, 'target' => $to, 'driver_name' => $this->driverName()]);
+        }
+        $sep = \DIRECTORY_SEPARATOR;
+        $path = ($basePath ?? \JKingWeb\Arsse\BASE."sql").$sep.static::schemaID().$sep;
+        // lock the database
+        $this->savepointCreate(true);
+        for ($a = $this->schemaVersion(); $a < $to; $a++) {
+            $this->savepointCreate();
+            try {
+                $file = $path.$a.".sql";
+                if (!file_exists($file)) {
+                    throw new Exception("updateFileMissing", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]);
+                } elseif (!is_readable($file)) {
+                    throw new Exception("updateFileUnreadable", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]);
+                }
+                $sql = @file_get_contents($file);
+                if ($sql===false) {
+                    throw new Exception("updateFileUnusable", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]); // @codeCoverageIgnore
+                }
+                try {
+                    $this->exec($sql);
+                } catch (\Throwable $e) {
+                    throw new Exception("updateFileError", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a, 'message' => $this->getError()]);
+                }
+                if ($this->schemaVersion() != $a+1) {
+                    throw new Exception("updateFileIncomplete", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]);
+                }
+            } catch (\Throwable $e) {
+                // undo any partial changes from the failed update
+                $this->savepointUndo();
+                // commit any successful updates if updating by more than one version
+                $this->savepointRelease();
+                // throw the error received
+                throw $e;
+            }
+            $this->savepointRelease();
+        }
+        $this->savepointRelease();
+        return true;
+    }
+
     public function begin(bool $lock = false): Transaction {
         return new Transaction($this, $lock);
     }

lib/Db/Driver.php

@@ -13,11 +13,13 @@ interface Driver {
     const TR_PEND_COMMIT = -1;
     const TR_PEND_ROLLBACK = -2;
     
-    public function __construct();
+    public static function create(): Driver;
     // returns a human-friendly name for the driver (for display in installer, for example)
     public static function driverName(): string;
     // returns the version of the scheme of the opened database; if uninitialized should return 0
     public function schemaVersion(): int;
+    // returns the schema set to be used for database set-up
+    public static function schemaID(): string;
     // return a Transaction object
     public function begin(bool $lock = false): Transaction;
     // manually begin a real or synthetic transactions, with real or synthetic nesting

lib/Db/SQLite3/Driver.php

@@ -22,7 +22,7 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
 
     public function __construct(string $dbFile = null) {
         // check to make sure required extension is loaded
-        if (!class_exists("SQLite3")) {
+        if (!self::requirementsMet()) {
             throw new Exception("extMissing", self::driverName()); // @codeCoverageIgnore
         }
         // if no database file is specified in the configuration, use a suitable default
@@ -30,9 +30,7 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
         $mode = \SQLITE3_OPEN_READWRITE | \SQLITE3_OPEN_CREATE;
         $timeout = Arsse::$conf->dbSQLite3Timeout * 1000;
         try {
-            $this->db = $this->makeConnection($dbFile, $mode, Arsse::$conf->dbSQLite3Key);
-            // enable exceptions
-            $this->db->enableExceptions(true);
+            $this->makeConnection($dbFile, $mode, Arsse::$conf->dbSQLite3Key);
             // set the timeout; parameters are not allowed for pragmas, but this usage should be safe
             $this->exec("PRAGMA busy_timeout = $timeout");
             // set other initial options
@@ -60,8 +58,14 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
         }
     }
 
+    public static function requirementsMet(): bool {
+        return class_exists("SQLite3");
+    }
+
     protected function makeConnection(string $file, int $opts, string $key) {
-        return new \SQLite3($file, $opts, $key);
+        $this->db = new \SQLite3($file, $opts, $key);
+        // enable exceptions
+        $this->db->enableExceptions(true);
     }
 
     public function __destruct() {
@@ -72,60 +76,41 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
         unset($this->db);
     }
 
+    public static function create(): \JKingWeb\Arsse\Db\Driver {
+        if (self::requirementsMet()) {
+            return new self;
+        } elseif (PDODriver::requirementsMet()) {
+            return new PDODriver;
+        } else {
+           throw new Exception("extMissing", self::driverName());
+        }
+    }
+
 
     public static function driverName(): string {
         return Arsse::$lang->msg("Driver.Db.SQLite3.Name");
     }
 
+    public static function schemaID(): string {
+        return "SQLite3";
+    }
+
     public function schemaVersion(): int {
         return $this->query("PRAGMA user_version")->getValue();
     }
 
     public function schemaUpdate(int $to, string $basePath = null): bool {
-        $ver = $this->schemaVersion();
-        if (!Arsse::$conf->dbAutoUpdate) {
-            throw new Exception("updateManual", ['version' => $ver, 'driver_name' => $this->driverName()]);
-        } elseif ($ver >= $to) {
-            throw new Exception("updateTooNew", ['difference' => ($ver - $to), 'current' => $ver, 'target' => $to, 'driver_name' => $this->driverName()]);
-        }
-        $sep = \DIRECTORY_SEPARATOR;
-        $path = ($basePath ?? \JKingWeb\Arsse\BASE."sql").$sep."SQLite3".$sep;
         // turn off foreign keys
         $this->exec("PRAGMA foreign_keys = no");
-        // lock the database
-        $this->savepointCreate(true);
-        for ($a = $this->schemaVersion(); $a < $to; $a++) {
-            $this->savepointCreate();
-            try {
-                $file = $path.$a.".sql";
-                if (!file_exists($file)) {
-                    throw new Exception("updateFileMissing", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]);
-                } elseif (!is_readable($file)) {
-                    throw new Exception("updateFileUnreadable", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]);
-                }
-                $sql = @file_get_contents($file);
-                if ($sql===false) {
-                    throw new Exception("updateFileUnusable", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]); // @codeCoverageIgnore
-                }
-                try {
-                    $this->exec($sql);
-                } catch (\Throwable $e) {
-                    throw new Exception("updateFileError", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a, 'message' => $this->getError()]);
-                }
-                if ($this->schemaVersion() != $a+1) {
-                    throw new Exception("updateFileIncomplete", ['file' => $file, 'driver_name' => $this->driverName(), 'current' => $a]);
-                }
-            } catch (\Throwable $e) {
-                // undo any partial changes from the failed update
-                $this->savepointUndo();
-                // commit any successful updates if updating by more than one version
-                $this->savepointRelease();
-                // throw the error received
-                throw $e;
-            }
-            $this->savepointRelease();
+        // run the generic updater
+        try {
+            parent::schemaUpdate($to, $basePath);
+        } catch (\Throwable $e) {
+            // turn foreign keys back on
+            $this->exec("PRAGMA foreign_keys = yes");
+            // pass the exception up
+            throw $e;
         }
-        $this->savepointRelease();
         // turn foreign keys back on
         $this->exec("PRAGMA foreign_keys = yes");
         return true;